Positional dependence of defect distribution in semipolar hydride vapor phase epitaxy-GaN films grown on patterned sapphire substrates

Abstract

We have investigated the position dependence of crystalline quality and defect distribution in a semipolar hydride vapor phase epitaxy (HVPE)-GaN film grown on a patterned sapphire substrate (PSS). Position-dependent X-ray microdiffraction (XRMD) measurement clearly revealed the periodic fluctuation of the lattice plane tilting in HVPE-GaN films. This correlated with the periodic distribution of (a + c)-type dislocations owing to the patterning pitch of the PSS as confirmed by transmission electron microscopy (TEM). In the three-dimensional reciprocal lattice space map, the diffuse streak exactly along the c-axis can be clearly detected, indicating the presence of basal plane stacking faults in HVPE-GaN films. Furthermore, we have quantitatively estimated the defect densities from the results of XRMD and TEM measurements. From the obtained results of XRMD and TEM measurements, the fluctuation of the lattice plane tilting and the defect distribution in HVPE-GaN films grown on two types of metalorganic vapor phase epitaxy-GaN templates will be discussed in detail.